HLA-DRB1 and myeloid sarcoma: To date, the *1501 allele of the highly polymorphic HLAclass II DRB1 gene is considered the main MS risk marker.Besides this allele, other DRB1 variants are associated withthe disease in European populations: *0301, *0405, *0801, *1303, etc., as wellas a number of alleles of HLA class I genes (HLA-A*0301, HLA-B*3701, *3801, aswell as *4402, HLA-C*05, and *07) [41].Genome-wide association studies (GWAS) proved most efficient in detecting newMS susceptibility markers outside the HLA locus.